JPH0195506A - On-load tap changer - Google Patents

Abstract

PURPOSE:To improve the reliability of abnormality detection by providing temperature detectors in a changeover switch oil tank and a transformer tank used upon tap changeover in loading and further providing externally of the tap changeover transformer an abnormality decision part for deciding any abnormality of the device on the basis of signals issued from the temperature detectors. CONSTITUTION:Temperature detectors 8, 21 are provided in an oil tank 4 for separation from insulating oil in a transformer body, which detect a temperature in the oil tank 4 of a changeover switch 2, that houses therein insulating oil 7 and an interruption part 5, and a temperature of the insulating oil in the transformer body. In addition, an abnormality decision part is provided, which monitors dangerous temperature in the oil tank 4 based upon the detected temperature signals by the temperature detectors 8, 21 to decide the presence of any accident and further evaluates reference temperature in the oil tank 4 of the changeover switch 2 from the rate of loading to the transformer to decide the presence of any trouble. Thus, the presence of any abnormality in the changeover switch 2 can securely be detected in an early time, and any severe accident can be prevented upon any abnormality occuring to improve the reliability of the abnormality detectors.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to an on-load tap changer, and particularly to a device for detecting the temperature of insulating oil in an oil tank of a changeover switch.

The present invention relates to an on-load tap switching device that monitors the presence or absence of an abnormality and prevents the abnormality from expanding.

゛ (Prior art) A load tap switching device installed in a transformer in a power transmission and distribution system is a device installed in a transformer when the load in the power transmission and distribution system fluctuates and the voltage change due to this fluctuation exceeds a certain limit. It is possible to keep the voltage of the power transmission and distribution system constant by switching the taps. Further, the on-load tap switching device provided in an industrial transformer is designed to switch the taps of the transformer according to the power required by the industrial equipment to supply the required force. This on-load tap changer is composed of a switching signal generator, an on-load tap changer, and an electric operation mechanism, and the on-load tap changer is further composed of a switching switch with a cutoff section housed in an oil tank and a tap selector. has been done.

In the on-load tap switching device having this configuration, the switching operation is outlined as follows. That is, when the isc pressure change exceeds a certain limit, a signal is first generated in the switching signal generator, and the mi-motion operating mechanism is started by this signal to drive the on-load tap changer.

As a result of step 7, the drive shaft of the on-load tap changer rotates, and this driving force moves the movable contact of the changeover switch away from one fixed contact and into the other fixed contact. Correspondingly, the tap selector switches from one tap to the other in a no-voltage state.By the way, if this on-load tap switching device breaks down, for example in a power transmission/distribution system such as a main line, it can cause a wide range of damage. If the on-load tap switching device breaks down, there is a risk of a power outage causing an accident that could spread further.

It is necessary to detect, recognize and deal with it as soon as possible.

Conventionally, as a failure detection means for tap changers under load, the insulating oil is decomposed due to an abnormal arc that occurs inside the switching switch oil tank, and a large amount of gas force5 is generated, and the oil flow and gas pressure are detected. There are also methods that use a current transformer to measure the magnitude of the current flowing through the tap changer during load to detect short circuits between taps.

[Problems to be Solved by the Invention] However, the conventional fault detection means for on-load tap changers as described above has the following drawbacks.

The switching switch of the on-load tap changer is installed in an oil tank to isolate it from the insulating oil of the transformer body, and the current is switched on and off frequently and at high speed within this oil tank. ~The contact group that opens and closes the current is often bridged between taps during operation, so a current limiting resistor is installed to reduce the current caused by the bridge. The current limiting resistor's temperature rises when energized, but the switching switch is operated at high speed to suppress this temperature rise. Therefore, the greater the number of switching times, the higher the probability of receiving mechanical damage due to high-speed switching.

For example, if the switching switch is damaged in some way and the switching operation stops midway through, the current limiting resistor will continue to be energized, and the oil temperature in the oil tank will rise, causing the switching switch contacts to rise. There is a strong possibility that this will cause thermal damage to the group oil tank and lead to a major accident such as a fire in the transformer.

Further, even if the current limiting resistor itself is blown out due to a rise in temperature, an abnormal arc will occur at the fused portion, raising the oil temperature in the oil tank, resulting in an accident similar to the above.

The above example is an example where there is mechanical damage, but as another example, if the on-load tap changer continues to change abnormally continuously, the oil temperature in the oil tank continues to rise.

It is also conceivable that the resistance will eventually melt and the result will be the same as the accident described above.

However, conventional failure detection means use oil flow, gas pressure, or Fi,'&! Since it captures secondary phenomena that follow an accident phenomenon such as current value, even if an accident is detected, the damage may have already spread and the on-load tap changer or transformer may not be protected. What's more, the accidents that have occurred are kept in the status of minor accidents.

Conventional detection methods cannot determine whether the accident is continuing to spread.

The present invention was made in order to solve the above-mentioned conventional problems, and its purpose is to provide an on-load tap changer with high reliability in abnormality detection that can prevent switching opening/closing from occurring. There is a particular thing.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention installs a temperature detector inside the switching switch oil tank of the on-load tap changer and inside the transformer tank, and The present invention is characterized in that an abnormality determining section is provided outside the switching transformer for determining an abnormality based on a detection signal from the temperature detector.

(Function) With this configuration, the abnormality determination section can detect an abnormality in the switching switch in a short time based on the oil temperature change inside the switching switch and the oil temperature change in the transformer body. Four major accidents can be predicted before they escalate into serious accidents.

(Embodiment) An embodiment of the on-load tap switching device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. Reference numeral 1 denotes an on-load tap changer, which is composed of a changeover switch 2 and a tap selector 3. The switching switch 2 includes an oil tank 4 that is isolated from the insulating oil in the tank of the transformer 20, a breaker 5' that switches on and off the current stored in the oil tank 4, and a current limiting resistor 6 that limits the current of the cutoff current. , and an insulating oil 7 filled in an oil tank 4. 8 is a temperature detector installed in the insulating oil 7 in the oil tank 4, and its detection signal is sent to an abnormality determination unit 9 installed outside the mineral oil tank 4.
sent to. 21 is a temperature detector provided in the insulating oil of the transformer 20, and its detection signal is similarly sent to the abnormality determination section 9. Abnormality Judgment Unit 9 Companies Based on the A-D conversion circuit 10 that converts electrical analog signals into digital signals and the digital signals of the respective detected temperatures, ■ Determines whether the current temperature in the oil tank 4 is a dangerous temperature or not. and.

■ The current temperature in the oil tank 4 is below the dangerous temperature.

Calculate whether this temperature is equal to or higher than the temperature determined by the load factor.

■ If there is an abnormality, there is an arithmetic determination unit 11 that determines whether the current abnormality will immediately lead to a serious accident based on the determination result of (■) above, and an abnormality display unit that displays the determination of failure or accident. It consists of 12.

The calculation and determination section 11 is the transformer section 200! ! It is configured to issue a command to the line breaker 13 which opens and closes the line.

FIG. 2 shows a temperature rise curve A in the transformer and a temperature rise curve B in the switching switch oil tank 4 regarding the operation of the on-load tap switching bag device configured as described above, and the calculation/judgment unit 11. This will be explained using FIG. 3 which shows a determination flowchart. During normal switching operation of the switching switch 2, the temperature inside the oil tank 4 changes as shown by the temperature rise curve B in FIG. 2 in accordance with the load factor.

Generally, the oil temperature in the switch switch oil tank is lower than the oil temperature in the transformer main body oil tank, so the dangerous temperature should be set at a value that exceeds the transformer main body oil temperature that matches the transformer main body load factor. These dangerous temperatures and temperature rise curves are transformers.

It is set according to the current carrying capacity of the switching switch.

Next, the operation of the calculation/judgment section 11 will be explained with reference to FIG.

The current oil temperature TL in the oil tank 4 of the transformer 20 is detected by the temperature detectors 21 and 8. If the temperature exceeds the dangerous temperature TR, it is determined that it is a serious accident and the line breaker 13 is activated to open the transformer 200 circuit.
Next, when the temperature TL is below the dangerous temperature TR, the load factor L1 of the transformer 20 determined from the dangerous temperature TR is calculated, and the standard temperature TL1 in the oil tank 4 that meets this load factor L8 is calculated, and the actual temperature is calculated. If the temperature TL in the oil tank 4 exceeds the standard temperature TL obtained by calculation, it is determined that there is an abnormality in the switching switch 2, and the abnormality display section 12 generates an alarm. Further, if the temperature TL in the oil tank 4 continues to rise, it is determined that a serious accident will occur, and the line breaker 13 is operated to open the circuit of the transformer 20.

According to this embodiment, a temperature detector 21 of the transformer 20 and a temperature detector 8 in the oil ia 4 of the switching switch 2 are provided.

The abnormality determination section 9 detects an abnormality in the oil temperature and the standard oil temperature at the load rate, and determines whether a major accident or malfunction has occurred in a certain period of time. Furthermore, even in the event of a failure, it can be predicted before it leads to a serious accident.

〔Effect of the invention〕

As described above, according to the present invention, the temperature in the oil tank of the switching switch, in which the breaker is housed together with the insulating oil in the oil tank separated from the insulating oil in the transformer main body, and the temperature of the insulating oil in the transformer main body are detected. Based on the temperature detection signal from these temperature detectors, dangerous temperatures in the oil tank are monitored, and accidents are determined based on this, and the oil tank of the transfer switch is An abnormality determination section that calculates the standard temperature within the switching switch and determines a failure based on this is provided, making it possible to quickly and reliably detect the presence or absence of an abnormality in the switching switch, and to further detect the presence or absence of an abnormality in the switching switch. A highly reliable on-load tap changer for detecting abnormalities that can prevent serious accidents in the event of an accident! i- can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a load tap switching device according to the present invention;
FIG. 2 is a characteristic diagram illustrating changes in oil temperature in the switching switch oil tank, and FIG. 3 is a flowchart of an abnormality determination method. 1... On-load tap changer, 2... Switching switch, 3
・・・Tip selector, 4...Oil tank, 5...Shutoff part, 6...Current limiting resistor, 7...Insulating oil, 8.21
...Temperature detector. 9... Abnormality determination unit, io... A-D conversion circuit, 11
... Calculation determination section, 12... Abnormality display section, 13...
Line breaker, 20...Transformer. Applicant's agent Patent attorney Takehiko Suzu Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] Temperature detectors are provided to detect the temperature in the oil tank of the switching switch, in which the breaker is housed together with the insulating oil in an oil tank that is separated from the insulating oil in the transformer main body, and the temperature of the insulating oil in the transformer main body. The dangerous temperature in the oil tank is monitored based on the temperature detection signal of the detector, and an accident is determined based on this, and the standard temperature in the oil tank of the switching switch is calculated from the load factor of the transformer. An on-load tap switching device characterized by comprising an abnormality determining section that determines.